The woman’s story was detailed in a case report published in September by International Journal of Infectious Diseases, LiveScience reported Thursday.

At first, the woman was diagnosed with a simple sinus infection. But when a course of antibiotics didn’t improve her symptoms, doctors recommend that she try saline nasal irrigation – an at-home remedy in which a saline solution is poured into the nose to clean mucus or allergens out of the sinuses. It can be performed with a handful of different devices, but the best known is probably the teapot-shaped neti pot.

Experts recommend using sterile saline or water for nasal irrigation, but the woman instead used tap water that had been filtered using an at-home water purifier, the report said.

A month later, she developed a quarter-sized rash on her nose that didn’t go away despite several dermatologist visits. Then, a year after she starting using the neti pot, she had a seizure, and scans revealed a lesion in her brain. After two surgeries and some testing, doctors finally determined that her brain has been infected by amoebas. Despite aggressive treatment, the woman died.

The woman was infected by the Balamuthia mandrillaris amoeba

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Balamuthia mandrillaris is an amoeba that can cause fatal infections.

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CDC

It wasn’t until after her death that testing revealed the precise amoeba responsible for the infection: Balamuthia mandrillaris. It’s an organism that can cause serious brain and spinal cord infection, according to the Centers for Disease Control and Prevention (CDC). It’s been found in dust and soil around the world and may also exist in water. It was first discovered by scientists in 1986 and since then, about 200 cases of Balamuthia infection have been diagnosed worldwide.

Right now, little is known about how people contract Balamuthia infections, the CDC website adds. But if someone does get one, the outlook is grim: “Due to the difficulty of diagnosis and severity of this infection, the fatality rate for Balamuthia infection is near 100%,” the authors wrote in the case report.

The authors suspected that the woman’s nasal irrigation provided a “route of entry” for the amoeba to get into her body. They can’t be 100% certain of this, the report added, because the water at the woman’s home was not tested for evidence of Balamuthia.

But there is past evidence to support this idea.

Other people have died after using neti pots with contaminated tap water

Because Balamuthia infection is rare, “people should just go about their normal lives” without panicking, he told LiveScience. But if they do use a neti pot, he added, they should “definitely use sterile water or saline.”